NEW YORK (CNNMoney.com) -
Will the scorned painkillers Vioxx and Bextra ever get back on the market? Will Celebrex ever shake its black box warning?

These arthritis drugs, produced by Merck and Pfizer, are all members of the same class, known as COX-2 selective non-steroidal anti-inflammatory drugs, or NSAIDs for short. The popular painkillers raked in billions of dollars for their makers before they ran into regulatory trouble, and the Food and Drug Administration is holding a meeting on Friday to glean more information on health risks.

The FDA isn't going to make any decisions on Friday about the fate of these drugs. But experts have been weighing the possibilities of an eventual market return for Merck's Vioxx and Pfizer's Bextra, and whether Pfizer's Celebrex will improve its status in the eyes of regulators.

The future of Vioxx

Analysts are mixed on the prospects for Vioxx:

"I'm not holding my breath, but I think there is a chance that Vioxx could come back," said Jami Rubin, analyst for Morgan Stanley.

Rubin said the "huge body of data" about the risk profile concerning Vioxx could be used to bring the drug back into the fold. But David Moskowitz, analyst for Friedman, Billings & Ramsey, said that Vioxx will "certainly not" be brought back, because of a wealth of evidence pointing to the drug's cardiovascular risks.

"The product seemed to cause high blood pressure compared to the other drugs, and Vioxx would be implicated as the more dangerous product [compared to other NSAIDs,]" said Moskowitz.

When asked about a Vioxx market return, Robert Hazlett, analyst for Suntrust Robinson Humphrey, said, "There is a chance that could occur. It is an outside chance, but there is a chance."

The NSAID trouble began with Merck's (down $0.42 to $33.92, Research) Vioxx, which totaled $2.5 billion sales in 2003, its last full year on the market. Merck, based in Whitehouse Station, N.J., pulled the drug off the market in September, 2004, after a study showed increased risk of heart attacks and strokes in patients taking the drug for at least 18 months. Since then, nearly 10,000 lawsuits have been filed against Merck by plaintiffs who blame the drug for heart attacks, fatal and non-fatal. So far, Merck has lost one case, won two, is retrying another case that ended in a hung jury, and has another case ongoing.

The future of Bextra

The trouble for Pfizer (down $0.62 to $25.72, Research) came to light a few months later, in April of 2005, when the FDA asked the New York-based drug giant to take Bextra, which totaled $1.3 billion in 2004 sales, off the market. Pfizer's Celebrex remains on the market to this day, but sales have been cut in half, to $1.7 billion in 2005 from $3.3 billion in 2004. In July of 2005, the FDA had Pfizer add a "black box," the most severe type of warning, to its Celebrex label to reflect risks of heart attacks, strokes and gastrointestinal bleeding.

Analysts weren't so rosy about a market return for Bextra. While Vioxx has a wealth of data, positive and negative, Bextra does not, so Pfizer would have to invest in expensive studies to demonstrate the drug's safety to regulators.

"Pfizer would have to run more clinical studies for [Bextra's return to market,] and the market has really shrunk to the point where it's doubtful that Pfizer would ever return the product to market," said Moskowitz of FBR.

The future of Celebrex

Celebrex remains on the market with a black box that warns of possibly fatal heart attacks, strokes and gastrointestinal bleeding. Analysts are mixed as to whether the warning is a permanent or temporary.

Rubin of Morgan Stanley said that not only will Celebrex always have that black box, but that someday all NSAIDs will carry it, including the over-the-counter ibuprofen. But Moskowitz of FBR believes that Pfizer might shake the warning by tapping its wealth of safety data concerning Celebrex, particularly with regard to the gastrointestinal risks.

Dr. Eric Matteson, NSAID expert and professor of medicine at the Mayo Clinic College of Medicine in Rochester, Minn., said that of all the major NSAIDs, Celebrex is definitely the safest and the only one that should still be available for patients.

"The concerns that led to Vioxx and Bextra being pulled from the market are grave concerns," said Matteson. "In my opinion, Celebrex is still on the market because the degree of cardiovascular events from Celebrex is not as high as Bextra and Vioxx. A drug like Celebrex is in a good position to remain on the market."

Dr. Mark Fendrick, NSAID expert and professor of internal medicine at the University of Michigan, said that Vioxx, Bextra and Celebrex were initially developed as alternatives to other NSAIDs like ibuprofen because they're easier, or intended to be easier, on the stomach. He said this fact is often overlooked amid the hype surrounding the fallen-from-grace blockbusters.

"If you have gastro-intestinal concerns, and you don't have heart concerns, and you're not taking aspirin, then that's where COX-2 inhibitors – Vioxx, Bextra, Celebrex – have a safety advantage," said Fendrick. "I do believe that in the absence of aspirin, Celebrex is safer for those with gastro-intestinal risk. They're no better in terms of pain relief, but they have an advantage for gastro-intestinal safety. If only we gave them to people to get the gastro-intestinal advantage, we wouldn't have this trouble."